TYMPANIC THERMOMETRY: A NON-INVASIVE MEASURE OF HEMISPHERIC ACTIVITY

This study was designed to evaluate the efficiency of the tympanic thermometry method in assessing asymmetric hemispheric activity during a verbal and a face-recognition task. Our method was intended to reproduce the findings of researchers who use computerized brain tomography techniques such as PET, BEAM and CBF studies to measure the brain metabolic activity of subjects engaged in lateralized tasks. These authors report that their subjects generally show relatively more metabolic activity in the hemisphere known to be specialized for the task, ie. in the left hemisphere during verbal tasks and in the right hemisphere during visuo-spatial tasks. These authors also report a beneficial effect of hemisphere bias on performance so that those subjects who follow the expected pattern of preferential hemispheric activation obtained superior performance scores.; In our study, we placed tympanic thermometers in the right and left ears of 22 high school students and recorded their ear temperatures while they were engaged in experimental tasks which involved either the recognition of word-like stimuli or the recognition of human faces. We found that our subjects tended to show a relatively elevated left ear temperature (indicating relatively more metabolic activity in the left hemisphere) during the verbal task and a relatively higher temperature in their right ear (indicating relatively more metabolic activity in their right hemisphere) during the face recognition task. This tendency however did not reach statistical significance. A positive effect of hemisphere bias on performance was also found during the face recognition task so that those of our subjects who showed a consistently elevated right ear temperature obtained superior performance scores. However we did not observe the expected relationship between elevated left ear temperature and performance scores during the verbal task. We propose that the differences between our findings and the findings of the computerized brain tomography studies can be explained by methodological differences between experimental tasks.